The ulnar nerve emanates from the neck, passes between the first rib and the clavicle, passes through the axilla, extends down the medial humerus through the posterior sulcus of the medial epicondyle of the humerus and between the ulnar bones, also called the nerve sulcus, to the forearm to innervate the ulnar half of the ring finger and all of the little finger, and has a branch in the axilla to the tiger’s mouth of the hand, which is an important nerve for the hand. In the elbow and the fibrous sheath of bone, the ulnar nerve passes through this canal, and the position of the ulnar nerve in the ulnar nerve groove is more fixed and not easy to move. If there is a fracture of the medial epicondyle of the humerus and ulnar eminence, it is easy to damage the ulnar nerve. After the fracture heals, the new bone or deformity heals, making the ulnar nerve groove innately shallow and flat, so that the ulnar nerve slides back and forth on the bone crest, and people who sit in office writing are prone to squeeze the ulnar nerve and develop chronic inflammatory manifestations. The disease starts slowly and begins with discomfort in the elbow of the sensory nerve, numbness and soreness in the distribution area of the innervation. In more severe cases, hyperalgesia, atrophy of the interosseous muscle and the interosseous muscle may occur. At this time, the thickened ulnar nerve can be palpated in the ulnar nerve groove, and there is oversensitivity on local percussion. In terms of treatment, if numbness of the fingers and inflexible hand movements occur, vitamin B1, 20 mg orally or by injection (100 mg by injection) three times a day and vitamin B12 200 mg intramuscularly should be administered, while reducing activities. Surgical methods can be used to move the ulnar nerve forward, but the forward ulnar meridian must not be under tension and fixed effectively, so that the ulnar nerve does not slide back and forth after surgery to prevent aggravating trauma.